A series of experiments is proposed to study drug dissociation, drug discrimination, and their central nervous system (CNS) correlates in goldfish, rats, and monkeys. The proposed research is comprised of four major and interrelated series of investigations: (1) relation of age and environmental variables to dissociation, (2) relation of task variables to dissociation, (3) relation between discrimination based on drug states and dissociation, and (4) central nervous system correlates of dissociation. (1) We will examine the influences of age of learning and length of retention interval on retention for responses learned either in a drug or normal state. We will also vary environmental complexity during the retention interval in order to assess interference effects upon forgetting. (2) To relate task variables and dissociation, we will study (a) dissociation of Pavlovian autonomic versus operant responses, (b) external stimulus variables in state dependency, (c) dissociation for higher order learning, and (d) a proposed dual-process attentional model for dissociation. (3) Our investigation of the relation between discriminations based on drug states and dissociation will address three basic issues: (a) the establishment of detection and behaviorally toxic discrimination thresholds for several standard dissociative drugs, (b) the possibility of training different responses to different drug states, or levels of a single drug, and (c) the possibility that drug dissociation is based upon the discriminable properties of drugs. (4) Study of central nervous system correlates of disociation will focus particularly of the reticular formation, and (b) electrophysiological studies of activity recorded during training and overtraining of dissociated learning. In order to insure the generality of our findings, we will attempt to use at least two of our three study species in each series of investigations. Specific experiments will utilize species best suited for the particular experimental situation.